Rocket and jet engines use the combustion of propellant chemicals to propel vehicles and missiles into or through Earth's atmosphere. To assure the proper functioning of such engines, extensive tests and static firings of engines are performed at ground based test facilities. During such static test firings, hydrocarbon fueled engines typically emit a high mass fraction of the pollutant carbon monoxide (“CO”) into the atmosphere where further reactions can form pollutant oxides of nitrogen (“NOx”). Also, particulate matter may be discharged as a result of incomplete combustion and the levels of such pollutants emitted into the atmosphere may be unacceptable. Additionally, depending upon the size of the engine, the testing may produce unacceptably high noise levels.